The present invention relates to an apparatus for playing back rotating recording mediums such for example as video discs, PCM audio discs, or the like, and more particularly to a device in such an apparatus for preventing a container case for the rotating recording medium from being erroneously inserted into the apparatus.
Known apparatus for playing back rotating recording mediums of the kinds described above (hereinafter referred to as a "disc") generally have a signal pickup head disposed over a turntable and movable radially across the disc placed on the turntable to reproduce signals recorded on the disc while the latter rotates at a high speed. According to one type of such disc playback apparatus, a jacket containing a disc is inserted into the apparatus to place the disc therein for reproducing the signals stored in the disc. When the disc is inserted, it is initially held over the turntable. When the disc is to be removed out of the apparatus, the disc is again supported over the turntable and a disc case or empty jacket is inserted into the apparatus while a disc support by which the disc is centrally supported is in a raised position, for thereby placing the disc into the disc case for removal. To prevent the disc case or jacket from being inserted in error, a jacket opening mechanism or jacket opener in the apparatus is locked to block the disc case or jacket against insertion while an attempt is being made to place the disc case into the apparatus when the disc support is in the lifted position, that is, when the power is turned off and the apparatus is in a disc playback mode.
The conventional jacket opener is locked by a locking mechanism at one side thereof only. When the disc case is forcibly pushed on, therefore, one side of the disc case tends to be forced in though the other side is locked by the locking mechanism. The disc case thus inserted is caused to swing laterally, or is blocked resiliently rather than rigidly, so that the operator does not feel any secure reaction indicative of the locked condition of the jacket opener. As a result, the operator tends to force the disc case into the apparatus when the jacket opener is actually locked and the disc case should not be inserted. Another problem is that the locking mechanism lacks a desired degree of mechanical strength.